Hitherto, as a transparent electrically conductive film-attached substrate used for a liquid crystal element, an element obtained by coating the surface of a glass substrate with tin-containing indium oxide (indium oxide doped with a small amount of tin; hereinafter referred to as "ITO") is used. The transparent electrode formed by pattering an ITO transparent electrically conductive film in a definite form is excellent in the transparency to visible light. However, since the transparent electrically conductive film has a large resistivity of an order of 10.sup.-4 .OMEGA.cm, there are problems the surface area must be increased, and for realizing a high precision and a high-speed response of a display, the thickness of the transparent electrode must be increased.
However, if the thickness of the transparent electrically conductive film decreases, it becomes difficult to form an electrode having a minute form with a good yield, and also since a remarkable difference in level is formed in the inside of a liquid crystal display by the transparent electrode, there is a problem that an inferior orientation occurs at a surrounding portion of the different level in the orientation treatment of a liquid crystal by rubbing, etc.
To overcome this problem, a transparent electrode of a three-layer structure comprising a silver thin layer having a low resistivity as an electrically conductive layer, the silver thin layer being sandwiched with ITO layers, in order to improve the transparency, is disclosed as a transparent electrode for a liquid crystal display in JP-A-114841 (the term "JP-A" as used herein means an "unexamined published Japanese patent application").
The conventional technique of using the thin film of silver (Ag) for an electrically conductive layer achieves a transparency (high visible light transmittance) and a low resistance characteristics together, but since a water resistance of silver is greatly low, there is a problem that when water enters from a crack of the film, the silver layer deteriorates by corrosion.